Patents for sun simulator :
1st US-Nasa patent 3,239,660:
https://patentimages.storage.googleapis.com/3d/d6/b5/5b8a27b4297469/US3239660.pdfhttps://patents.google.com/patent/US3239660A/en%3E>In a sun simulator system, it is desirable to provide means for varying the intensity of illumination over a relatively wide range without change in the spectral distribution of the illumination, so that the simulator may be used to simulate not only sunlight, but also earthlight and moonlight. In order to provide sufficient illumination to simulate sunlight over a practicably large area, it is necessary to employ plural light sources, and it is desirable to control the intensity of illumination by varying the number of the light sources that are energized, thereby avoiding changes in the spectral distribution of the light output of the simulator, and maintaining a relatively high degree of efficiency.2nd US patent: US3325238A (Sun simulator machine)
https://patentimages.storage.googleapis.com/d3/a1/00/5921e930d46d89/US3325238.pdf3rd US patent : US3247367A
https://patentimages.storage.googleapis.com/95/87/ba/52da943ea67d97/US3247367.pdfhttps://m.youtube.com/watch?v=dH-_34DHbB0 